In the Cardiac-Renal-Pulmonary Clinic of Northwestern University, an experiment was begun in October, 1972 to study the impact of a computerized medical record summary system (NUCRSS) on process and outcome of care. 419 randomly selected patients were randomly assigned to two groups; an experimental group (NUCRSS available) and a control group (NUCRSS absent). Approximately 300 variables per subject, representing parameters of process and outcome of care, were collected, entered into a computer data base and cleaned. Because the experimental and control groups have remained intact, new data for the 479 subjects are now being collected on a selective basis emphasizing outcome of care. All data (new and old) are being analyzed to ascertain the effects of NUCRSS on process and outcome of care. Initial analysis of a few variables in the existing data base has yielded encouraging results.